Add RELATIVE_ORIENTATION sensor implementation on macOS to //device/generic_sensor

device/generic_sensor/platform_sensor_relative_orientation_using_accelerometer.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_RELATIVE_ORIENTATION_USING_ACCELEROMETER_H_
+#define DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_RELATIVE_ORIENTATION_USING_ACCELEROMETER_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/timer/timer.h"
+#include "device/generic_sensor/platform_sensor.h"
+
+namespace device {
+
+class SensorSharedBufferReader;
+
+// Implementation of relative orientation PlatformSensor using accelerometer.
+// This is a single instance object per browser process which is created by
+// The singleton PlatformSensorProvider. If there are no clients, this instance
+// is not created.
+class PlatformSensorRelativeOrientationUsingAccelerometer
+    : public PlatformSensor {
+ public:
+  // Construct a platform sensor of type RELATIVE_ORIENTATION, given a buffer
+  // |mapping| where readings will be written.
+  PlatformSensorRelativeOrientationUsingAccelerometer(
+      mojo::ScopedSharedBufferMapping mapping,
+      PlatformSensorProvider* provider);
+
+  mojom::ReportingMode GetReportingMode() override;
+  PlatformSensorConfiguration GetDefaultConfiguration() override;
+  // Can only be called once, the first time or after a StopSensor call.
+  bool StartSensor(const PlatformSensorConfiguration& configuration) override;
+  void StopSensor() override;
+
+ protected:
+  ~PlatformSensorRelativeOrientationUsingAccelerometer() override;
+  bool CheckSensorConfiguration(
+      const PlatformSensorConfiguration& configuration) override;
+
+ private:
+  void CreateAccelerometerCallback(scoped_refptr<PlatformSensor> accelerometer);
+  void PollForData();
+
+  SensorReading reading_;
+  // Repeating timer for data polling.
+  base::RepeatingTimer timer_;
+  scoped_refptr<PlatformSensor> accelerometer_;
+  std::unique_ptr<SensorSharedBufferReader> accelerometer_reader_;
+
+  DISALLOW_COPY_AND_ASSIGN(PlatformSensorRelativeOrientationUsingAccelerometer);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_RELATIVE_ORIENTATION_USING_ACCELEROMETER_H_